1. Field of the Invention
The present invention relates to a system and method for switching permanent virtual connection (PVC), and, more particularly, to a system and method for controlling switching of PVC in an asynchronous transfer mode (ATM) switching network.
2. Description of the Related Art
Generally, the PVC is a connection path in which an originating terminal and a terminating terminal, or parties to be connected are fixed. When setting of the PVC path or the like is modified, it is necessary to modify setting by individual PVCs to be modified every time modification occurs. Thus, to enhance efficiency of the modification, it is sufficient to previously provide a plurality of settings such as PVC paths, and selectively use one of them.
An example of conventional PVC switching systems is disclosed in Japanese Patent Application Laid-Open No. 4-23648. The PVC switching system disclosed therein is to previously register a plural sets of combinations of connection pairs of PVC in a packet switching network. Then, one set is specified from the registered sets of connection pairs, allowing it to perform communication using the PVC registered in the specified set. When the specification of the set is changed, that is, when the PVC is changed over to another, all PVCs become once unavailable for communication.
A PVC switching system described in Japanese Patent Application Laid-Open No.8-181701 automatically selects the optimum intra-network connection path for PVC in an ATM switching network. That is, each of individual PVCs is monitored for its status, and the optimum path in the network is automatically selected when a failure or the like is detected to change over connection from one PVC to another.
In addition, a PVC switching system described in Japanese Patent Application Laid-Open No. 6-37809 causes one or more changed-over PVCs with priority to correspond to individual PVC logic channels in a packet switching network. In this way, it is possible to attain backup of computer services at multiple points. That is, when switching of PVC is instructed, it is to change over connection of PVC for the PVC logic channel for which switching is necessary for the specified priority. In other words, connection switching control is performed for the PVC logic channel under operation.
The conventional PVC switching system described in Japanese Patent Application Laid-Open No. 4-23648 allows only PVC registered for the selected connection set to perform communication. Thus, it has a disadvantage such that switching on PVC in only part of the network cannot be attained. In addition, even if the same PVC as that prior to switching exists after switching when PVC is switched, that PVC cannot be available for communication for a while.
A conventional PVC switching system described in Japanese Patent Application Laid-Open No. 8-181701 is to automatically select the optimum path in the network for individual PVCs. Therefore, there is a disadvantage that the administrator cannot switch parts or all of PVCs in a batch at his/her discretion.
Furthermore, a conventional PVC switching system described in Japanese Patent Application Laid-Open No. 6-37809 performs switching only for applicable PVCs among PVCs operating according to the specified priority under operation. Thus, there is a disadvantage that the administrator cannot necessarily change connection at his/her discretion.
Therefore, the PVC switching systems in the specifications described above have a disadvantage that, when parts or all of PVCs in the network are connected, disconnected, or changed for paths, the administrator cannot perform switching of them in batch and systematically at his/her discretion without affecting the communication state of PVCs not subject to switching control.